all you need to do is insert the bgproperties="fixed" in the <body header. If you need to see how it is done, just go to the page and right click on the main frame and select view source. The line you need is again in the body header.

A fixed background can also be achieved with a Cascading Style Sheet: <link rel=stylesheet href="your_style_sheet.css type="text/css">or a Style block in the <head></head> section: <style type="text/css"></style>. The style command is the same: body {background-attachment: fixed} Also, a style command can be placed "inline": <body style="background-attachment: fixed"> However, I see no real advantage to the Style approach unless you were using a CSS to affect many pages and didn't want to type bgproperties="fixed" many times.
P.S. Netscape(4.0) doesn't execute a fixed background any way I've tried (let me know if you find a way). Good Day. kenezmn